1. Field of Invention
This invention relates generally to traffic intersections and more particularly to displaying a representation of a traffic intersection.
2. Description of Related Art
Traffic intersections may be designed by laying out the roadways and intersection area on a computer using a computer aided design (CAD) application. Once the roadways have been initially defined, the intersection may be tested to determine whether certain types of vehicle can pass through the intersection without encroaching on curbs or islands making up the intersection. The testing may involve generating a vehicle swept path by producing a scaled representation of the vehicle and then simulating passage of the design vehicle through the intersection to determine whether any encroachment exists. Should changes to the initial roadway definition be necessary to eliminate encroachments, features of the intersection would have to be manually modified and then the vehicle swept path regenerated.
Designing traffic roundabouts is particularly problematic. A roundabout is a traffic intersection having a central island surrounded by a circulatory roadway and having one or more approach roadways. The circulatory roadway includes at least one lane and should be sized to provide for adequate maneuvering space for different vehicles that will use the intersection. A designer of a roundabout will generally take into account a defined design vehicle that is expected to use the roundabout and may also face other constraints that should be simultaneously satisfied. For example, a fastest path of a defined passenger vehicle may be taken into account to ensure that smaller vehicles are not able to operate at unsafe speeds through a roundabout that is sized to permit passage of a large articulated vehicle.
Satisfying several constraints may involve defining an initial size and layout of the roundabout, which is then tested to determine whether the design vehicle is able to maneuver through the intersection without encroaching on the central island, outer edges of the circulatory roadway, or any other outer edges of the intersection. Should the design vehicle be able to pass without encroachment, the fastest path of a smaller design vehicle may also be determined and speeds of the vehicle along the path computed to determine whether the intersection meets safety criteria. Should changes to the initial layout be necessary to satisfy either of these constraints, the process may have to be repeated for each change, resulting in an iterative process that may become tedious and time consuming.
There remains a need for improved methods for producing representations of traffic intersections.